Centering gauge



Feb. 23, 1932. A. BUCHMULLER' 1,846,787

CENTERING GAUGE Filed Sept. 19. 1.930

lllII IIUIllli!IIIIHIIIIIIIIIIIIIIIIII Patented Feb. 23, 1932 s'rArss UNITE,

ALFRED nucnnrt'innnn, or couz, NEAR DRIER, GERMANY, Assidnon on ron'rY PER on-u'r 'ro :en'rnn ZETTELMEYER, on oouz, raisinszany, T' nn'r-Y rnnicn nr mo MRS. M. wanna, or Tarzan, GERMANY, TWENTY rnn cnnr T MB-S. on. n. Brennan, i or TRIER, GERMANY, AND TWENTY'PER onus TOMRS. nn. H. consrnu', ior' snnm'u- LICHTEBFELDE, GERIMAIQ'Y cnnrnnnve GAUGE Application filed September 19, 1930, Serial No. 483,144, and in Germany'nugust 9, 1928. v

three screws thereof outwards until the three legged gauge seized in the hole. With the aid of a pair of compasses, one hmb of which is constructed as a feeler, the centre was determined on the leaden core inserted in the marked and centre V three-legged gauge, punched or pricked. In the case of small holes a suitably shaped piece of flat iron is l usuallyndriven into the hole until it makes a tight lit and the centre marked in the same way and centre punched.

This method of findlng centres is, however, very inaccurate, for In marking and centre .220 punching the centre found, more or less deviation from the true position occurs according to thenature of the constructional material used. 5 The centre punch and the surface to be marked never lie exactly in thesame plane.

Further complications arise when one or more points pitched at a given angle from the centre'have to be determined in. this way. It has, therefore, already beengproposed to determine the centres of holes and the like by means of an instrument having three simultaneously, adjustable steps and an adjustable centre punch mark. The amountof eccentricity present could not, however, be meas ured with the known instruments. I

Thegauge according to the present invention is provided with stops which are adjustable independently of eachother in radial slots and acentre hole or indentation which is placed in the same plane of the surface on which the gauge bears. The periphery of the-disc-shaped instrument is also graduated, so that not only the centre of a hole but also an eccentric point can be determined at any desired angle. 7

Another advantage, of the gauge according to the present invention is that it "can also be used on cylindrical pieces of work or .parts thereof. 1 The stops, which are attached to the underside :of the instrument,

- have for this purpose flats on their inner sides so as to fit the cylindrical parts, theirouter sides being wedge-shaped for insertion into holes. I w a Y 7 A constructional .form of the invention is shown by way of example in'the accompanying: drawings, in which 1 is a plan view from the underside of I the lnstrument. i

Fig- 2 is a vertical section on the line 25-2 of Fig. 1, the-instrument being shown resting on a hollowcylinder, and V Fig. 3. is a top planview of the instrument. Thecircular disca contains at equiangular distances apart three radial slotsbl, and b which start close to thecentre. of the disc and extend almost to its edge. These slots are provided along their sides on the under part of the disc .(see' Fig. 1) with scales c 0 and c reading, forexample, from Oto 40 millimeters, In these slots 6 ,6 and b slide the downwardly extending stops (P, d

and (P, which are adapted to belocked in position by clamping the screws a passing through the slots 6 b -andb and milled nuts 7 on thetop of the disc. As'is known,

at least three stops'are necessary to be able to center the gauge in a round opening. The stops 6Z (Z and (Z? are provided with suitable Vernier scales which in conjunction with the scales c c 0 permit of fine adjustmentup to say a tenth of a millimeter. 7

Between the two radial slots 6 and b is a longer slot 9, which extends to thecentre of the disc and acts as a guide to an upper slide it. One side of the slot 9 is provided on the top of the disc (see Fig.3) with a scale heading from, say 0 to 50 millimetres. vThe slide 72. can be locked in any position by meansof a screw i'and a milled nut 7c underneath. The slide h is in the, form of a short pointer and carries along its tangential edge 8 a scale t, which acting in conjunction with the scale Z, after: the fashion of a'vernier, enables the slide to be accurately adjusted to one tenth of a millimetre. The slide it is provided .with

the particular point sought inside or outside with a scale m readingfrom0 to 180.

h a centre hole or indentation 1*, which indicates of the tubular piece of Work "0. On their in-.

sides the stops have flat sides 32, which when the instrument is fitted on to a cylinder 9 (indicated by dot'and dash lines in Fig. 2)

lie at a'tangent to the external surface of such cylinder.

The instrument is used in the following Way:

To ascertain the centre of a hole the three stop members (Z (Z and (Z on the lower side of the disc are-adjusted by means of the scales c c 0 and Z engraved thereon and are then looked in position by tightening up the milled nuts 7: the centre of the hole is then found on the upper side of the disc in the middle of the slideh thereon.

If the slide 71. be novvused, which can be moved sideways towards the scale Z provided by loosening the central lovver milled nut is, any eccentricity lying Within range can'be ascertained. g

The slide it When in position at the inner extremity of the slot 9 is located in the exact centre with respect to the three edges 41, and

a circle may be described on the piece 0 Which is concentric to the hole in Wh1ch the gauge rests, whereas if the slide h is moved outwardly a given distance, a circle described on the piece 0 With the po'int'r as the centre will have a definite eccentricity With the said hole. I a

' ii To enable points to be "determined by a fixed angle the graduation angle m on the 7 1ea hand upper side is used in conjunction With the centre of the slide It determined by the centre hole r.

For example in a gear box it'is possible that the individual shafts be not only parallel to each other but one may lie above the other or at 'an angle to the other. If two shafts are located at anangle to a third shaft, the

- graduated scale m is used to fix the angle of the centre point of one shaft with-respect to theother by laying a straight edge from the point r to the centre point ofone shaft and [another straight edge. from point r to the centre point of the other shaft and measuring the included angle. '7 l/Vhen the instrument is used With a cylinjdricalprojection or the stump end of a shaft, such as g the fiat sides 20 of the three stop members (P, d and (Z 'act as hearing points.

I claim: r ..1. In a gauge for marking out centers, a disc provided with at least three radial slots, an independently adjustable stop radially 'movable in each slot,a slide havinga center hole andineans for mounting said slide radiallly adjustable on said disc. "2. A gauge for marking out centers comprising in combination a disc-shaped memher having at least threeradiallyand equiangularly disposed guidevvays formed therein, stops movable along said guideways, said disc-shaped member also having an addi tional guideWay' formed therein extending radially from the center of said member, and a slide having a. center hole, mounted on said additional guideWay and adapted to move therein.

3. In a centering gauge, a disc body containing at least three radial slots, an independently adjustable stop radially'm'ov'able in each slot, and a radially adjustable slide, having a center hole, means for mounting said slide on said disc and means for severally locking said slide and stopsin anydesired position. v

4. A centering gauge comprising in combination a disc-shaped member having at least three radially and equi-angularly disposed guideways formed therein, stops movable, along said guideways, said disc-shaped member having an additional guidevvay formed therein and extending radially from the center of said member, and a slide movable in said additional guideway and having a center hole therein and means for severally locking said slide and stops in position.

7 5. In a centering gauge, a disc provided With at least three radial slots, an independently adjustable stop radially movable in each slot, a radially adjustable slide,having a center hole, means for mounting said slide on said disc said slide and said disc having cooperating parts of a Vernier scale formed thereon.

1 6. In a centering gaugepthe combination of a disc-shaped member provided with at least three radially disposed slots, independently ad ustable stops radially movable in said slots, a radially adjustable slide having a center hole means for mounting said slide on said disc and said slide and said disc having cooperating parts of 'a Vernier scale formed thereon, and means for severally locking said slideand stops'in position.

7. A gauge for marking out centerscomprising in combination a disc-shaped mem her having at least three radial and equi-angularly disposed guideways therein, stops movable along said guideways, said discshaped member also-having an additional guideway formed therein extending radially from the center of the said member, anda slide movable along said additional guide- Way' and having a center hole therein, said disc-shaped member'having scales formed thereon adjacent said slide and stops and means for severally locking said slide and stopsin position. 1

8. A gauge for marking out centers, comprising a disc-shaped member having at least three radially and equi-angularly disposed guide'ways formed therein, depending stops movable Within said guideways, said discshaped member having an; additionaliguideway formed therein and extending radially from the center of said member; and 'a slide having a center holemovable' in said additional guideway.

9.- A gauge for marking out centers comprising a disc-shaped member having at least three radially and equi-angularly disposed guideways formed therein, depending stops movable within said guideways, said discshaped member having an additional guide-. Way formed therein and extending radially slide movable along said additional guideway, said slide having a center hole, said disc-shaped member having scales 'formed thereon adjacent said guideways, said slide being provided with a tangential edge havin a scale formed" thereon, the said scale ad acent the additional guideway cooperating with the said scale on the tangential edge.

11. A gauge for marking out centers as defined by claim 10 having means for locking said stops and slide in position.

12. A gauge for marking out centers comprising a disc-shaped member having a scale formed on the periphery thereof and having at least three radially and equi-angularly V disposed guideways formed therein, said member having scales formed thereon adj acent said guideways and stops movable Within said guideways, said disc-shaped member also having an additional guideway formed thereinextending radially from the center of said member and a slide movable along said additional guideway, said slide having a center hole, said slide being provided with a tangential edge having a scale formed thereon, said scale adjacent the additional guideway cooperating with the said scale on the tangential edge, and means for locking said stops and slidein position.

In testimony that I claim theforegoing as my invention, I have signed my name.

ALFRED BUCHMULLER.

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